Genetic improvement of timothy digestibility by breeding requires an effective and reliable selection procedure. The general objective of this study was to evaluate the concentrations of four fiber components (neutral detergent fiber, acid detergent fiber, acid detergent lignin, hemicellulose, and cellulose) and four ratios involving these concentrations (acid detergent lignin over hemicellulose, acid detergent lignin over cellulose, acid detergent lignin over the sum of hemicellulose and cellulose and hemicellulose over cellulose) as selection criteria to improve timothy digestibility without affecting plant biomass. Selected genotypes and populations derived from them were evaluated in a field experiment. Significant variability was observed among genotypes for all nine traits. Divergent phenotypic selection for seven of the traits (all except hemicellulose and hemicellulose over cellulose) produced groups of genotypes that consistently differed for the trait used as the selection criterion. Selection criteria that involved acid detergent lignin were the most effective in identifying genotypes with consistent differences in in vitro true digestibility. Genotypes selected for high or low values of each criterion were intercrossed to produce progeny populations. Five of the nine pairs of divergent populations were consistently different for the trait used as the selection criterion. Selection for acid detergent lignin over cellulose was the most effective in producing populations with consistent differences (22 to 32 g kg-1 DM) in in vitro true digestibility, with reduced values of this ratio associated with increased digestibility. This was mainly due to a reduction of the concentrations of lignin and neutral detergent fiber, particularly in the stem fraction, resulting in greater stem digestibility. Among the criteria examined here, the ratio of acid detergent lignin over cellulose therefore seems to be the most promising for phenotypic

No description available.

No description available.

Avian point counts were conducted in tall-grass prairie fragments and adjacent grassland and agricultural matrix habitat in southern Manitoba. Bird density/abundance was compared between habitat types, while variables within prairie at local, patch or landscape level were modeled to determin avian habitat selection. Prairies and matrix grassland habitat supported the same number of species in both years, and densities of all focal bird species were the same in non-native grasslands as compared with native tall-grass prairies. Overall species richness in tall-grass prairies was mainly driven by vegetation variables. Variable responses to habitat structure and composition between avian species indicate that managing grasslands to promote heterogeneity is important to sustain a diverse assemblage of avian species. As individual species were affected most strongly by vegetation structure and richness, it follows that management of prairie vegetation through techniques such as grazing and prescribed burning could optimize habitat usability for birds.

The Yellow Quill Mixed Grass Prairie Preserve is a remnant of an endangered community that is located in southwestern Manitoba and owned by The Nature Conservancy of Canada. In 2005 and 2006, this study was conducted to investigate the effect that the currently-practiced twice-over rotational cattle grazing regime is having on the carabid beetles and spiders. This study primarily compared grazed and ungrazed treatments on three paddocks. A secondary experiment investigated whether the spring graze, fall graze, or the combination of the two had the greatest impact on the carabids and spiders. Three periods were examined in three periods each season: before grazing had begun, after the spring graze, and after the fall graze. A total of 81 species of carabids and 156 species of spiders were recorded, including potentially new provincial records (two carabid species and 20 spider species). Seventy two species of plants were recorded in the study.

Avian point counts were conducted in tall-grass prairie fragments and adjacent grassland and agricultural matrix habitat in southern Manitoba. Bird density/abundance was compared between habitat types, while variables within prairie at local, patch or landscape level were modeled to determin avian habitat selection. Prairies and matrix grassland habitat supported the same number of species in both years, and densities of all focal bird species were the same in non-native grasslands as compared with native tall-grass prairies. Overall species richness in tall-grass prairies was mainly driven by vegetation variables. Variable responses to habitat structure and composition between avian species indicate that managing grasslands to promote heterogeneity is important to sustain a diverse assemblage of avian species. As individual species were affected most strongly by vegetation structure and richness, it follows that management of prairie vegetation through techniques such as grazing and prescribed burning could optimize habitat usability for birds.

The Yellow Quill Mixed Grass Prairie Preserve is a remnant of an endangered community that is located in southwestern Manitoba and owned by The Nature Conservancy of Canada. In 2005 and 2006, this study was conducted to investigate the effect that the currently-practiced twice-over rotational cattle grazing regime is having on the carabid beetles and spiders. This study primarily compared grazed and ungrazed treatments on three paddocks. A secondary experiment investigated whether the spring graze, fall graze, or the combination of the two had the greatest impact on the carabids and spiders. Three periods were examined in three periods each season: before grazing had begun, after the spring graze, and after the fall graze. A total of 81 species of carabids and 156 species of spiders were recorded, including potentially new provincial records (two carabid species and 20 spider species). Seventy two species of plants were recorded in the study.

No description available.

No description available.

Two field studies assessed sward dynamics to legume removal with and without Canada thistle and other broadleaf plants (i.e. forbs). When grown in mixtures with grass, alfalfa had a more consistent negative yield response to legume removal compared to clover swards. Within established pastures, total forage (i.e. legume and grass) had little association with Canada thistle, but was instead associated with perennial forbs such as dandelion. Grass responses (biomass and protein yield) in established swards were unable to compensate for legume removal up to 2 years after spraying. Relative yield ratios were used to identify weed and legume thresholds, and indicated the removal of legume and Canada thistle did not always negatively impact forage production. Instead, select positive yield responses were observed depending on the initial composition, growing conditions and abundance of weed and legume. / Rangeland and Wildlife Resources